nixpkgs/pkgs/os-specific/linux/kernel/generic.nix

{
  buildPackages,
  pkgsBuildBuild,
  callPackage,
  perl,
  bison ? null,
  flex ? null,
  gmp ? null,
  libmpc ? null,
  mpfr ? null,
  pahole,
  lib,
  stdenv,
  rustc-unwrapped,
  rustPlatform,
  rust-bindgen-unwrapped,
  # testing
  emptyFile,
  nixos,
  nixosTests,
}@args':

let
  overridableKernel = lib.makeOverridable (
    # The kernel source tarball.
    {
      pname ? "linux",

      src,

      # The kernel version.
      version,

      # Allows overriding the default defconfig
      defconfig ? null,

      # Legacy overrides to the intermediate kernel config, as string
      extraConfig ? "",

      # Additional make flags passed to kbuild
      extraMakeFlags ? [ ],

      # enables the options in ./common-config.nix and lib/systems/platform.nix;
      # if `false` then only `structuredExtraConfig` is used
      enableCommonConfig ? true

      , # kernel intermediate config overrides, as a set
      structuredExtraConfig ? { },

      # The version number used for the module directory
      # If unspecified, this is determined automatically from the version.
      modDirVersion ? null,

      # An attribute set whose attributes express the availability of
      # certain features in this kernel.  E.g. `{ia32Emulation = true;}'
      # indicates a kernel that provides Intel wireless support.  Used in
      # NixOS to implement kernel-specific behaviour.
      features ? { },

      # Custom seed used for CONFIG_GCC_PLUGIN_RANDSTRUCT if enabled. This is
      # automatically extended with extra per-version and per-config values.
      randstructSeed ? "",

      # A list of patches to apply to the kernel.  Each element of this list
      # should be an attribute set {name, patch} where `name' is a
      # symbolic name and `patch' is the actual patch.  The patch may
      # optionally be compressed with gzip or bzip2.
      kernelPatches ? [ ],
      ignoreConfigErrors ?
        !lib.elem stdenv.hostPlatform.linux-kernel.name or "" [
          "aarch64-multiplatform"
          "pc"
        ],
      extraMeta ? { },
      extraPassthru ? { },

      isLTS ? false,
      isZen ? false,
      isLibre ? false,
      isHardened ? false,

      # easy overrides to stdenv.hostPlatform.linux-kernel members
      autoModules ? stdenv.hostPlatform.linux-kernel.autoModules or true,
      preferBuiltin ? stdenv.hostPlatform.linux-kernel.preferBuiltin or false,
      kernelArch ? stdenv.hostPlatform.linuxArch,
      kernelTests ? { },

      stdenv ? args'.stdenv,
      buildPackages ? args'.buildPackages,
      pkgsBuildBuild ? args'.pkgsBuildBuild,

      ...
    }@args:

    # Note: this package is used for bootstrapping fetchurl, and thus
    # cannot use fetchpatch! All mutable patches (generated by GitHub or
    # cgit) that are needed here should be included directly in Nixpkgs as
    # files.

    let
      # Combine the `features' attribute sets of all the kernel patches.
      kernelFeatures = lib.foldr (x: y: (x.features or { }) // y) (
        {
          efiBootStub = true;
          netfilterRPFilter = true;
          ia32Emulation = true;
        }
        // features
      ) kernelPatches;

      commonStructuredConfig = import ./common-config.nix {
        inherit lib stdenv version;
        rustAvailable = lib.meta.availableOn stdenv.hostPlatform rustc-unwrapped;

        features = kernelFeatures; # Ensure we know of all extra patches, etc.
      };

      intermediateNixConfig =
        configfile.moduleStructuredConfig.intermediateNixConfig
        # extra config in legacy string format
        + extraConfig
        # need the 'or ""' at the end in case enableCommonConfig = true and extraConfig is not present
        + lib.optionalString enableCommonConfig stdenv.hostPlatform.linux-kernel.extraConfig or "";

      structuredConfigFromPatches = map (
        {
          structuredExtraConfig ? { },
          ...
        }@args:
        if args ? extraStructuredConfig then
          throw ''
            Passing `extraStructuredConfig` to the Linux kernel (e.g.
            via `boot.kernelPatches` in NixOS) is not supported anymore. Use
            `structuredExtraConfig` instead.
          ''
        else
          {
            settings = structuredExtraConfig;
          }
      ) kernelPatches;

      # appends kernel patches extraConfig
      kernelConfigFun =
        baseConfigStr:
        let
          configFromPatches = map (
            {
              extraConfig ? "",
              ...
            }:
            extraConfig
          ) kernelPatches;
        in
        lib.concatStringsSep "\n" ([ baseConfigStr ] ++ configFromPatches);

      withRust = ((configfile.moduleStructuredConfig.settings.RUST or { }).tristate or null) == "y";

      configfile = stdenv.mkDerivation {
        inherit
          ignoreConfigErrors
          autoModules
          preferBuiltin
          kernelArch
          extraMakeFlags
          ;
        pname = "linux-config";
        inherit version;

        generateConfig = ./generate-config.pl;

        kernelConfig = kernelConfigFun intermediateNixConfig;
        passAsFile = [ "kernelConfig" ];

        depsBuildBuild = [ buildPackages.stdenv.cc ];
        nativeBuildInputs = [
          perl
          gmp
          libmpc
          mpfr
          bison
          flex
        ]
        ++ lib.optional (lib.versionAtLeast version "5.2") pahole
        ++ lib.optionals withRust [
          rust-bindgen-unwrapped
          rustc-unwrapped
        ];

        RUST_LIB_SRC = lib.optionalString withRust rustPlatform.rustLibSrc;

        # e.g. "defconfig"
        kernelBaseConfig =
          if defconfig != null then defconfig else stdenv.hostPlatform.linux-kernel.baseConfig or "defconfig";

        makeFlags = import ./common-flags.nix {
          inherit
            lib
            stdenv
            buildPackages
            extraMakeFlags
            ;
        };

        postPatch = kernel.postPatch + ''
          # Patch kconfig to print "###" after every question so that
          # generate-config.pl from the generic builder can answer them.
          sed -e '/fflush(stdout);/i\printf("###");' -i scripts/kconfig/conf.c
        '';

        preUnpack = kernel.preUnpack or "";

        inherit (kernel) src patches;

        buildPhase = ''
          export buildRoot="''${buildRoot:-build}"

          # Get a basic config file for later refinement with $generateConfig.
          make $makeFlags \
              -C . O="$buildRoot" $kernelBaseConfig \
              ARCH=$kernelArch CROSS_COMPILE=${stdenv.cc.targetPrefix} \
              $makeFlags

          # Create the config file.
          echo "generating kernel configuration..."
          ln -s "$kernelConfigPath" "$buildRoot/kernel-config"
          DEBUG=1 ARCH=$kernelArch CROSS_COMPILE=${stdenv.cc.targetPrefix} \
            KERNEL_CONFIG="$buildRoot/kernel-config" AUTO_MODULES=$autoModules \
            PREFER_BUILTIN=$preferBuiltin BUILD_ROOT="$buildRoot" SRC=. MAKE_FLAGS="$makeFlags" \
            perl -w $generateConfig
        ''
        + lib.optionalString stdenv.cc.isClang ''
          if ! grep -Fq CONFIG_CC_IS_CLANG=y $buildRoot/.config; then
            echo "Kernel config didn't recognize the clang compiler?"
            exit 1
          fi
        ''
        + lib.optionalString stdenv.cc.bintools.isLLVM ''
          if ! grep -Fq CONFIG_LD_IS_LLD=y $buildRoot/.config; then
            echo "Kernel config didn't recognize the LLVM linker?"
            exit 1
          fi
        ''
        + lib.optionalString withRust ''
          if ! grep -Fq CONFIG_RUST_IS_AVAILABLE=y $buildRoot/.config; then
            echo "Kernel config didn't find Rust toolchain?"
            exit 1
          fi
        '';

        installPhase = "mv $buildRoot/.config $out";

        enableParallelBuilding = true;

        passthru = rec {
          module = import ../../../../nixos/modules/system/boot/kernel_config.nix;
          # used also in apache
          # { modules = [ { options = res.options; config = svc.config or svc; } ];
          #   check = false;
          # The result is a set of two attributes
          moduleStructuredConfig =
            (lib.evalModules {
              modules = [
                module
              ]
              ++ lib.optionals enableCommonConfig [
                {
                  settings = commonStructuredConfig;
                  _file = "pkgs/os-specific/linux/kernel/common-config.nix";
                }
              ]
              ++ [
                {
                  settings = structuredExtraConfig;
                  _file = "structuredExtraConfig";
                }
              ]
              ++ structuredConfigFromPatches;
            }).config;

          structuredConfig = moduleStructuredConfig.settings;
        };
      }; # end of configfile derivation

      kernel = (callPackage ./build.nix { inherit lib stdenv buildPackages; }) {
        inherit
          pname
          version
          src
          kernelPatches
          randstructSeed
          extraMakeFlags
          extraMeta
          configfile
          modDirVersion
          ;

        config = {
          CONFIG_MODULES = "y";
          CONFIG_FW_LOADER = "y";
          CONFIG_RUST = if withRust then "y" else "n";
        };
      };

    in
    kernel.overrideAttrs (
      finalAttrs: previousAttrs: {

        passthru =
          previousAttrs.passthru or { }
          // extraPassthru
          // {
            features = kernelFeatures;
            inherit
              commonStructuredConfig
              structuredExtraConfig
              extraMakeFlags
              isLTS
              isZen
              isHardened
              isLibre
              ;
            isXen = lib.warn "The isXen attribute is deprecated. All Nixpkgs kernels that support it now have Xen enabled." true;

            # Adds dependencies needed to edit the config:
            # nix-shell '<nixpkgs>' -A linux.configEnv --command 'make nconfig'
            configEnv = finalAttrs.finalPackage.overrideAttrs (previousAttrs: {
              depsBuildBuild =
                previousAttrs.depsBuildBuild or [ ]
                ++ (with pkgsBuildBuild; [
                  pkg-config
                  ncurses
                ]);
            });

            tests =
              let
                overridableKernel = finalAttrs.finalPackage // {
                  override =
                    args:
                    lib.warn (
                      "override is stubbed for NixOS kernel tests, not applying changes these arguments: "
                      + toString (lib.attrNames (lib.toFunction args { }))
                    ) overridableKernel;
                };
                /*
                  Certain arguments must be evaluated lazily; so that only the output(s) depend on them.
                  Original reproducer / simplified use case:
                */
                versionDoesNotDependOnPatchesEtcNixOS =
                  builtins.seq
                    (nixos (
                      { config, pkgs, ... }:
                      {
                        boot.kernelPatches = [
                          (builtins.seq config.boot.kernelPackages.kernel.version { patch = pkgs.emptyFile; })
                        ];
                      }
                    )).config.boot.kernelPackages.kernel.outPath
                    emptyFile;
                versionDoesNotDependOnPatchesEtc =
                  builtins.seq
                    (import ./generic.nix args' (
                      args
                      // (
                        let
                          explain = attrName: ''
                            The ${attrName} attribute must be able to access the kernel.version attribute without an infinite recursion.
                            That means that the kernel attrset (attrNames) and the kernel.version attribute must not depend on the ${attrName} argument.
                            The fact that this exception is raised shows that such a dependency does exist.
                            This is a problem for the configurability of ${attrName} in version-aware logic such as that in NixOS.
                            Strictness can creep in through optional attributes, or assertions and warnings that run as part of code that shouldn't access what is checked.
                          '';
                        in
                        {
                          kernelPatches = throw (explain "kernelPatches");
                          structuredExtraConfig = throw (explain "structuredExtraConfig");
                          modDirVersion = throw (explain "modDirVersion");
                        }
                      )
                    )).version
                    emptyFile;
              in
              {
                inherit versionDoesNotDependOnPatchesEtc;
                testsForKernel = nixosTests.kernel-generic.passthru.testsForKernel overridableKernel;
                # Disabled by default, because the infinite recursion is hard to understand. The other test's error is better and produces a shorter trace.
                # inherit versionDoesNotDependOnPatchesEtcNixOS;
              }
              // kernelTests;
          };

      }
    )
  );
in
overridableKernel